I've changed persistance for my local postgresql db and no longer have this issue, but concerning your questions - I've been using the default demo
persistant settings.
As for changes made to the system - I had issues with human task server and another one with no human task listed
in jbpm-console and resolved it by changing taskorm.xml file in human task core 5.3 jar to the one from human task core 5.4.
Another thing was configuring the human task server for to use mina implementation, localhost, port 1923.
Before that, I was messing with starting many processes so maybe there was messed up data in the db, however
I didn't know how to clean the embadded h2 database. I'm not sure but I don't think I've made any more
changes in the system